Hi,
I just started using Picoscope, with Win 98 to parallel port. Using latest software.

Displaying the output of an ac power supply which reads 13.5 V rms (i.e.approx 19V pk) on a meter I get a display (with a 10x probe) of +20V peak to -45V peak. Exactly the same display with connections reversed.
With an AAA cell I get 1.87V with normal connection, and -26.77V reversed.
Also with a half cycle of the 60Hz there seems only to be about 8 samples. It jumps from the zero-crossing to about half amplitude in a straight line although there seem to be more points around the peak.

(I checked the parallel port after reading a previous post and it is set at Normal, 378H and IRQ 7)
Thanks,
John Duffus

Thanks for the .psd files. Well, I think either the ADC or the parallel port on the PC is faulty.

If you could try the ADC-40 on a different PC and confirm that the problem still exists then you've almost definitely got a faulty ADC. If thats the case contact our returns department for an RMA number so that we can test it in the lab.